Question 1

Steriod hormone response elements (HREs)are __________ ,which,when bound to _____________,alter gene expession at the level of ________________.

Accepted Answer

A) intron sequences;activated hormone receptor;translation 
B) nuclear proteins;hormone;transcription 
C) plasma membrane proteins;hormone;transcription 
D) sequences in DNA;receptor-hormone complex;replication 
E) sequences in DNA;receptor-hormone complex;transcription 
A) intron sequences;activated hormone receptor;translation 
B) nuclear proteins;hormone;transcription 
C) plasma membrane proteins;hormone;transcription 
D) sequences in DNA;receptor-hormone complex;replication 
E) sequences in DNA;receptor-hormone complex;transcription

Question 2

The force that drives an ion through a membrane channel depends on the:

Accepted Answer

A) charge on the membrane. 
B) difference in electrical potential across the membrane. 
C) size of the channel. 
D) size of the ion. 
E) size of the membrane. 
A) charge on the membrane. 
B) difference in electrical potential across the membrane. 
C) size of the channel. 
D) size of the ion. 
E) size of the membrane.

Question 3

The G protein involved in visual signal transduction is:

Accepted Answer

A) a leukotriene. 
B) transducin. 
C) arrestin. 
D) rhodopsin. 
E) a GTP receptor. 
A) a leukotriene. 
B) transducin. 
C) arrestin. 
D) rhodopsin. 
E) a GTP receptor.

Question 4

Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except:

Accepted Answer

A) chemically induced mutagenesis. 
B) chromosomal rearrangements. 
C) during a viral infection cycle. 
D) elimination of their start signals for translation. 
E) radiation-induced mutation. 
A) chemically induced mutagenesis. 
B) chromosomal rearrangements. 
C) during a viral infection cycle. 
D) elimination of their start signals for translation. 
E) radiation-induced mutation.

Question 5

Signals carried by hormones must eventually be terminated;the response continues for a limited time.Discuss three different mechanisms for signal termination,using specific systems as examples.

Accepted Answer

Hormonal responses may be terminated by

Question 6

Briefly describe the key features of the acetylcholine receptor channel.

Accepted Answer

There are five homologous subunits,each

Question 7

Explain how amplification of a hormonal signal takes place;illustrate with a specific example.

Accepted Answer

Amplification occurs when one molecule o

Question 8

Which of the following is not a feature of signal transduction?

Accepted Answer

A) Integration of multiple pathways toward the same downstream response 
B) Signal amplification 
C) Covalent binding between the ligand and the receptor 
D) Desensitization or adaptation of the receptor 
E) Variable affinity for different signaling components 
A) Integration of multiple pathways toward the same downstream response 
B) Signal amplification 
C) Covalent binding between the ligand and the receptor 
D) Desensitization or adaptation of the receptor 
E) Variable affinity for different signaling components

Question 9

What are cyclins? What is their role in the regulation of the cell cycle?

Accepted Answer

Cyclins are regulatory subunits of prote

Question 10

Which of the following is not true for G protein-coupled receptors (GPCRs)?

Accepted Answer

A) Agonists mimic the effect of the natural ligand. 
B) Antagonists block the normal effect of the natural ligand. 
C) GPCRs interact with heterodimeric G proteins. 
D) GPCRs are have seven transmembrane helices. 
E) There exist >100 orphan GPCRs in the human genome with no known ligand. 
A) Agonists mimic the effect of the natural ligand. 
B) Antagonists block the normal effect of the natural ligand. 
C) GPCRs interact with heterodimeric G proteins. 
D) GPCRs are have seven transmembrane helices. 
E) There exist >100 orphan GPCRs in the human genome with no known ligand.

Question 11

Which of the following statements concerning cyclins is not correct?

Accepted Answer

A) They are activated and degraded during the cell cycle. 
B) They are regulatory subunits for enzymes that catalyze the phosphorylation of proteins. 
C) They can become linked to ubiquitin. 
D) They catalyze the phosphorylation of proteins. 
E) They contain specific amino acid sequences that target them for proteolysis. 
A) They are activated and degraded during the cell cycle. 
B) They are regulatory subunits for enzymes that catalyze the phosphorylation of proteins. 
C) They can become linked to ubiquitin. 
D) They catalyze the phosphorylation of proteins. 
E) They contain specific amino acid sequences that target them for proteolysis.

Question 12

Ubiquitin is a:

Accepted Answer

A) component of the electron transport system. 
B) protease. 
C) protein kinase. 
D) protein phosphorylase. 
E) protein that tags another protein for proteolysis. 
A) component of the electron transport system. 
B) protease. 
C) protein kinase. 
D) protein phosphorylase. 
E) protein that tags another protein for proteolysis.

Question 13

Explain the importance of membrane rafts in cell signaling pathways.

Accepted Answer

Rafts are membrane regions enriched in s

Question 14

Autophosphorylation of receptor tyrosine kinases depends on which of the following?

Accepted Answer

A) Dimerization of the receptor 
B) ATP 
C) Ligand binding 
D) Transmission of conformational changes through the membrane 
E) All of the above 
A) Dimerization of the receptor 
B) ATP 
C) Ligand binding 
D) Transmission of conformational changes through the membrane 
E) All of the above

Question 15

Which of the following is not involved in signal transduction by the $\beta$-adrenergic receptor pathway?

Accepted Answer

A) Cyclic AMP synthesis 
B) GTP hydrolysis 
C) GTP-binding protein 
D) Protein kinase 
E) All of the above are involved. 
A) Cyclic AMP synthesis 
B) GTP hydrolysis 
C) GTP-binding protein 
D) Protein kinase 
E) All of the above are involved.

Question 16

Which of the following statements concerning receptor enzymes is correct?

Accepted Answer

A) They are not usually membrane-associated proteins. 
B) They contain an enzyme activity that acts on a cytosolic substrate. 
C) They contain an enzyme activity that acts on the extracellular ligand. 
D) They have a ligand-binding site on the cytosolic side of the membrane. 
E) They have an active site on the extracellular side of the membrane. 
A) They are not usually membrane-associated proteins. 
B) They contain an enzyme activity that acts on a cytosolic substrate. 
C) They contain an enzyme activity that acts on the extracellular ligand. 
D) They have a ligand-binding site on the cytosolic side of the membrane. 
E) They have an active site on the extracellular side of the membrane.

Question 17

GTP-binding proteins play critical roles in many signal transductions.Describe two cases in which such proteins act,and compare the role of the G proteins in each case.

Accepted Answer

GTP-binding proteins are self-inactivati

Question 18

Which of the following is not one of the general types of signaling mechanisms found in multicellular organisms?

Accepted Answer

A) Gated ion channels 
B) Receptor tyrosine kinases 
C) G protein-coupled receptors 
D) Receptor cAMP cyclases 
E) Adhesion receptors 
A) Gated ion channels 
B) Receptor tyrosine kinases 
C) G protein-coupled receptors 
D) Receptor cAMP cyclases 
E) Adhesion receptors

Question 19

Which of the following is true of gated ion channels?

Accepted Answer

A) Each channel can allow 10 million ions per second through the membrane. 
B) The gating mechanism involves piston-like movement of the transmembrane helices. 
C) Each channel lets both positive and negative ions flow through the pore. 
D) Closing of the gate requires phosphorylation of the channel protein. 
E) Gated channels only respond to intracellular ligands. 
A) Each channel can allow 10 million ions per second through the membrane. 
B) The gating mechanism involves piston-like movement of the transmembrane helices. 
C) Each channel lets both positive and negative ions flow through the pore. 
D) Closing of the gate requires phosphorylation of the channel protein. 
E) Gated channels only respond to intracellular ligands.

Question 20

What is a Scatchard plot,and how can it be used to determine the number of receptor molecules on a cell and their affinity for a ligand?

Accepted Answer

Cells are mixed with varying concentrati

Exam 12: Biosignaling

Steriod hormone response elements (HREs)are __________ ,which,when bound to _____________,alter gene expession at the level of ________________.

The force that drives an ion through a membrane channel depends on the:

The G protein involved in visual signal transduction is:

Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except:

Signals carried by hormones must eventually be terminated;the response continues for a limited time.Discuss three different mechanisms for signal termination,using specific systems as examples.

Briefly describe the key features of the acetylcholine receptor channel.

Explain how amplification of a hormonal signal takes place;illustrate with a specific example.

Which of the following is not a feature of signal transduction?

What are cyclins? What is their role in the regulation of the cell cycle?

Which of the following is not true for G protein-coupled receptors (GPCRs)?

Which of the following statements concerning cyclins is not correct?

Ubiquitin is a:

Explain the importance of membrane rafts in cell signaling pathways.

Autophosphorylation of receptor tyrosine kinases depends on which of the following?

Which of the following is not involved in signal transduction by the β\betaβ -adrenergic receptor pathway?

Which of the following statements concerning receptor enzymes is correct?

GTP-binding proteins play critical roles in many signal transductions.Describe two cases in which such proteins act,and compare the role of the G proteins in each case.

Which of the following is not one of the general types of signaling mechanisms found in multicellular organisms?

Which of the following is true of gated ion channels?

What is a Scatchard plot,and how can it be used to determine the number of receptor molecules on a cell and their affinity for a ligand?

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Steriod hormone response elements (HREs)are ____ ,which,when bound to _,alter gene expession at the level of __________.

Which of the following is not involved in signal transduction by the $\beta$ -adrenergic receptor pathway?